Thermoplastic egg package



July 28, 1970 c. L.WHl1 'EFORD 3,522,@61

THERMOPLASTIC EGG PACKAGE Filed Oct. 5, 1966 l8 INVENTOR.

CARLTON L.WHlTEFORD ATTORNEY.

3,522,061 THERMOPLASTIC EGG PACKAGE Carlton L. Whiteford, New Canaan, Conn., assignor to Poly-Pal: Corporation of America, Springdale, Conu., a corporation of Delaware Filed Oct. 3, 1966, Ser. No. 583,796 The portion of the term of the patent subsequent to June 21, 1983, has been disclaimed Int. Cl. B65d 85/32 US. Cl. 99-177 12 Claims ABSTRACT OF THE DISCLOSURE There is disclosed a package comprising a plurality of avian eggs, a container enclosing and resiliently seating the eggs and a gaseous atmosphere within the container and about the eggs providing protection against deterioration and cushioning therefor. The container has top and bottom receptacle portions for receiving a portion of one of the eggs. The components have sealing means to provide releasable substantially gas-tight engagement therebetween and an individual sealed cell for each of the eggs. The portions of the bottom component include resilient seating means providing support for the eggs and permitting the flow of gas thereabout. The gaseous atmosphere comprises about 96-9975 percent of nitrogen and about 4-025 of oxygen, on a weight basis.

The present invention relates to packaging and, more particularly, to packages of perishable and frangible articles.

It is well known that numerous goods, and especially foodstuifs, tend to deteriorate to a greater or lesser degree in an atmosphere of air. Eggs, for example, are particularly susceptible to the adverse effects of the atmosphere and begin to deteriorate immediately upon being laid. Accordingly, it is highly desirable to insulate eggs and other perishable goods from the atmosphere as soon as possible. Moreover, it is desirable to do so in a package which is simple and inexpensive to manufacture, yet one which will provide protection against breakage or damage to frangible articles.

One method which has been employed to insulate certain perishable goods from the deleterious influences of air is to package the goods under vacuum conditions. However, this vacuum method has proven disadvantageous where the articles contain volatile components and, in the case of eggs, because the vacuum must be drawn gradually so as not to explode the eggs. In addition, packaging the articles in vacuo eliminates the partial cushioning efiect normally provided by a gaseous atmosphere, thus necessitating the use of additional cushioning means.

It has also been proposed to package, ship and store perishable items in an atmosphere of gas which will inhibit if not prevent spoilage. Recently, commercial shipping of fruits and vegetables in atmospheres of high nitrogen content has been quite prevalent. However, bulk packaging of articles in an inert gas affords little continuing advantage to a purchaser since opening the package to remove one of several items will generally result in loss of the protective atmosphere for the remaining items.

Accordingly, it is an object of the present invention to provide a novel and relatively economical package for perishable goods wherein the goods have a reduced tendency to spoil.

It is also an object to provide such a package which affords physical protection to the goods therein against normal impacts and permits visual inspection of the contents.

Another object is to provide such a package wherein a United States Patent Ice plurality of articles are effectively individually packaged so that one or more articles may be removed without destroying the protection for the remaining articles.

Other objects and advantages will be readily apparent from the following detailed description and the attached drawing wherein:

FIG. 1 shows a partly detailed, partly phantom perspective view of an egg carton embodying the present invention and in which two cells have been opened by removal of a portion of the cover;

FIG. 2 is a side elevational view of the carton illustrated in FIG. 1 with a portion broken away for clarity of illustration; and

FIG. 3 is a diagrammatic illustration of the locking engagement of the receptacle components.

It has now been found that the foregoing and related objects can be readily attained in a package of at least one perishable article and generally a plurality of such articles, which includes a container of thermoplastic material enclosing and seating the articles and having top and bottom receptacle components. Each of the receptacle components provides a cooperating receptacle portion receiving a portion of the article, and the components have sealing means thereon providing releasable, substantially gas-tight engagement therebetween. A gas in the receptacle portions surrounds the article and contains at least 85 percent by volume of an inert gas preventing deterioration of the perishable articles. To contain the gaseous atmosphere, the material of the components is substantially impermeable to the inert gas.

By packaging the frangible and perishable goods in a relatively inert atmosphere in accordance with the present invention, the adverse eifects of an oxygen-containing atmosphere are avoided Without sacrificing the desirable cushioning effects of a gaseous atmosphere in a closed container. Exemplary of the inert gases which are suitable for packaging of various items are carbon dioxide, nitrogen, and helium. Mixtures of such gases have also been found to be suitable. The specific gas selected will depend upon the particular item being packaged. For example, nitrogen is preferred for most items because of its relatively low cost and all-around advantages.

Due to the mechanism by which the deterioration of eggs is believed to proceed, it has also been found to be beneficial to provide a relatively humid atmosphere for eggs. When a humid atmosphere is provided, it is necessary to do so at a level which is a compromise between the level which best retards the loss of water from the egg and that which will avoid the significant growth of molds. From such a standpoint, about 85 percent relative humidity at degrees Fahrenheit has been found to be a suitable limit. Although it may be considered desirable to eliminate completely oxygen from the gaseous atmosphere for some applications, generally this is unnecessary from a practical standpoint since it has been found that less than one-half of 1 percent of oxygen in the package is satisfactory and in some cases as much as 1 to 2 percent of oxygen, and even up to 15 percent, may be acceptable. In fact, when anaerobic fermentation is a danger, it is beneficial to maintain from about 0.25 to about 4.0 percent of oxygen in the protective atmosphere.

The thermoplastic material which is chosen for use in the fabrication of the containers used in the present packages will depend upon the particular inert gas used therein. The ideal thermoplastic is one which is not only readily thermoformed but which also provides an essentially impermeable barrier to the passage of the inert gas contained within the package. Satisfactory packages can, however, be achieved when plastics exhibiting less gas impermeability are used by coating the material with a suitable material. Although laminates of thermoplastic materials may have the desired high levels of impermea'bility to various gases, such materials generally are difficult to thermoform since the differences in the coeflicients of thermal expansion of the laminated materials tend to cause various defects in the finished product.

When nitrogen is employed, polyvinylidene chloride is a preferred material since it may be thermoformed and is a good barrier to the flow of nitrogen gas, and it is suitable for the fabrication of structures having varying degrees of rigidity. A polyvinylidene chloride copolymer resin sold by W. R. Grace and Company under the trademark Cryovac is advantageously employed. Other thermoplastic materials which provide acceptable barriers to nitrogen passage include coated cellophane, rubber hydrochloride and polyesters. Polyvinyl chloride, polyethylene, polypropylene, and polystyrene are desirable films from a forming standpoint but have a relatively high permeability to nitrogen when used alone so that coating or laminating is desirable. However, the preferred films from a nitrogen standpoint may not be advantageous for other inert gases or where the atmosphere contains a mixture of gases so that the properties of the various materials should be reviewed. Thus, coatings may prove advantageous to provide gas impermeable membranes on otherwise permeable but readily formable sheet material providing the other desired physical characteristics.

To form the container sections, thermoforming of a thermoplastic sheet is preferably employed. Coatings, if any, can be applied after forming by spraying, or before forming it not volatile at the forming temperature. The container sections of this invention can be nested and stacked one within another for economic transit and do not require any setting-up operations prior to being filled. As an alternative to forming the sections individually, the top and bottom sections of the carton can be molded together with an integral hinge being formed simultaneously therebetween by use of a polyallomer resin. The latter method is, of course, most feasible when a single thermoplastic sheet material is to be employed for both sections of the container.

Once filled with the articles, the container is closed in the desired atmosphere, sealing each article with its surrounding atmosphere of inert gas within the enclosure which is formed. The article is thereby sealed in a protective atmosphere as well as being resiliently suspended and protected against rattling so that spoilage and breakage are materially reduced.

Although many means may be used to provide the desired engagement of the container components in a gastight seal including heat sealing, the preferred containers are not only gas-tight but also provide ready access to the contents thereof. It is furthermore desirable in the case of multicellular containers to make provision for access to a limited number of the contents without disturbing the contents sealed in other portions of the package. Accordingly, interfitting portions are provided on the two components which may be press-fitted together to form a gastight package. Thus, an axially extending annular rim on one component in telescopic engagement with a cooperating recess in the other receptacle component is provided. By providing a peripheral beveled flange around the entrance to the recess defined by the receptacle portion in either one or both of the carton halves and by providing a mating beveled surface on the periphery of the entrance to the complementary recessed portion, excellent gas-tight seals can be obtained by twisting and pressing the cell halves together. It is obvious, however, that the utilization of such a method requires that at least one-half of each cell unit be free to rotate about its own axis. Thus, if a multicellular unit is to be produced, it is necessary that each of the cell halves in either the top or bottom portion of the container be independent and not rigidly connected to adjacent cells.

In a preferred embodiment of the present invention, the mechanical seal is obtained by providing an annular rim or protrusion about the entrance portion of the cell halves or receptacle portions of one of the container components which is press-fitted into the annular entrance portion of the complementary cell half of the other component to unite the receptacle components in telescopic relationship. In such an embodiment, unavoidable slight imperfections, i.e., imperfect circles, inherent in the formation or manufacture of the receptacle components, tend to reduce the probability of obtaining truly gas-tight cells. An elfective seal is best achieved by providing an annular recess adjacent to the aforementioned rim which provides the necessary flexibility to allow the annular rim to adjust to the imperfection of the mating part so that a tight fit is obtained over the entire circumference of the interfitted portion of the cell halves despite such manufacturing variations.

To lock the components together against inadvertent opening during normal handling of the container, an inwardly-directed annular projection is provided on the female component about its article-receiving recess which deflects the annular rim by pressing upon it. In this manner, this deflecting pressure must be overcome to disengage the annular rim from the recess.

If so desired, the web portions of the components between the receptacle portions may be weakened so as to permit facile severing of individual cells without disturbing the seals of the remaining cells. In addition, it is also desirable to provide one component, preferably the top component, with longitudinal and transverse V- or U-shaped grooves in the web portion between adjacent receptacle portions to compensate for longitudinal centerto-center variations between complementary receptacle portions in each component. Although such grooves provide the necessary flexibility, die cuts may be utilized to ensure automatic adjustability while also permitting facile severance of one receptacle portion without disturbing other components.

It is also desirable that the thermoplastic used in at least one component be resiliently deformable so as to provide a cushioning enclosure for the articles. For overall best results, according to this invention, it is presently preferred to make one carton section (preferably the cover) of a relatively rigid, high-strength thermoplastic material so as to lend structural strength to the carton and to protect the goods contained within from impact forces, and the other section (preferably the bottom section) of a relatively flexible, high-strength thermoplastic material which will cushion the enclosed article. It will be appreciated that it is possible to employ the same thermoplastic for the entire carton by using a thicker or more rigid form of the plastic for one half and a more resilient form for the other. In addition, an auxiliary stiffening or strengthening member may be utilized to enhance the overall rigidity of the container.

Any suitable method may be used to produce the packages disclosed herein. A very simple method of doing so involves placing the articles into the container in a normal atmosphere, purging substantially all of the air from the container with a stream of the inert gas or the gaseous atmosphere, and then quickly closing and sealing the container to prevent the escape of gaseous atmosphere established therein. As an alternative, the containers could be loaded with the articles and the cartons sealed, all within an atmosphere of the gas to be contained within the cartons, or, after loading the container in air, it may be passed into a chamber filled with the gaseous atmosphere and therein sealed.

As previously indicated, the package of the present invention provides desirable storage conditions for various perishable articles and is particularly advantageous for avian eggs. Although it is not fully understood why replacement of the air surrounding eggs with an atmosphere composed at least in part of an inert gas decreases the rate at which such eggs perish and become unsuitable for consumption, it is believed that the presence of the substantially inert atmosphere and the substantial absence of oxygen avoids certain reactions and physical changes which lead to decomposition of the egg.

Numerous complicated and subtle changes are apparently responsible for the deterioration and loss of palatability of eggs. Among them, and possibly the most significant, are: (1) biological processes and reactions, (2) a change in pH, (3) loss and movement of water, and (4) the escape of gases such as carbon dioxide, ammonia and possibly nitrogen. Like many biological processes and reactions, those that occur within an egg in most instances require a supply of oxygen. Thus, by removing and replacing the oxygen in the surrounding environment with substantially inert atmosphere, such biological phenomena may be inhibited to a substantial extent.

Carbon dioxide and bicarbonates of sodium and potassium comprise a buffer system within the albumen of the egg. With the loss of carbon dioxide through the egg shell and the reduction in concentration of bicarbonate ions, the buffer system progressively becomes disorganized and the pH of the system tends to rapidly increase from approximately neutral to an alkaline value. Accordingly, by inhibiting the escape of carbon dioxide the effectiveness of the buffer system should be maintained and the pH of the system should therefore remain substantially constant.

It is believed that the escape of carbon dioxide, ammonia, nitrogen and also water will continue only so long as concentration differentials exist. Thus, when equilibrium is attained between the egg and its surrounding environment, the losses of these essential components from the egg should cease. In a package such as that of the present invention, the volume of gas surrounding each egg is relatively small and equilibrium concentrations are readily attained with the loss of only a small proportion of the components from the interior of the egg.

Referring now in detail to the attached drawing, FIGS. 1 and 2 illustrate a container employing the invention for use as an egg package and generally indicated by the reference numeral 10. The container includes a top component A of relatively rigid, high-strength thermoplastic material and a bottom component B of relatively resilient or flexible thermoplastic material. Each of the components A, B contains 12 receptacle portions or cups respectively designated by the numerals 20, 11. These receptacle portions 20, 11 are interconnected by web portions 23, 12 respectively which are dimensioned so as to each receive a portion of the eggs placed within the container. In this particular embodiment, the configuration and dimensioning of the receptacle portions 20, 11 has been varied so as to enhance the specialized operation of each, as will be pointed out more fully hereinafter.

Turning first in detail to the top component A, this preferably is fabricated from a transparent synthetic plastic material so that the eggs or other articles may be inspected visually. As best seen in the partially diagrammatic illustration of FIG. 3, the receptacle portion 20 has a curvilinear entrance portion 21 closely adjacent the bottom component B and is provided with an inwardlydirected annular bead 25. In addition, the web portion 23 is corrugated as indicated by the numeral 24 so as to increase the strength of the top component and also pro vide facile means for gripping the edges thereof for purposes of opening one or more cells. Die cuts 22 are provided in the web 23 between adjacent pairs of receptacle portions 20 to facilitate removal of a portion of the top component A to open one or more cells without disturbing the cells of the adjacent receptacles. As can be seen, the side walls of the receptacle portions 20 have inwardly projecting ribs formed therein which serve to position the egg and minimize rattling or movement thereof.

The bottom component B has an annular lip or bead generally designated by the numeral 14 which projects upwardly from the plane of the web 12 about the cylinrical entrance portion 13 of the receptacle portions 11.

The inner wall of the lip 14 continues in the plane of the entrance portion 13 and its outer wall 14a is spaced therefrom so as to permit inward deflection thereof. At the juncture between the lip 14 and the web 12 is an annular channel or recess 16.

As best seen in FIG. 3, when the top component A is assembled to the bottom component B, the annular lip 14 is press-fitted into the entrance portion 21 of the receptacle portions 20 in the top compartment. Minor variations in dimensioning occurring due to the process of manufacture may be compensated for by the annular groove or recess 16 which acts as a tension spring to hold the outer wall 14a of the lip 14 against the inner surface of the entrance portion 21. The inside diameter of the cylindrical entrance portion 21 of the top component A is made smaller than the outside diameter 14a of the hollow lip portion of the lower component B.

To lock the two components together against disassembly during normal handling, this embodiment includes the annular bead 25 on the top component A which acts as a locking ring by distorting the outer wall 14a of the lip 14. Due to the relatively greater rigidity and stiffness of the thermoplastic material from which the top component A is formed, the ring 25 deflects the material of the lip 14 and then locks into the arcuate contour which it has formed. As a result of the press-fitted connection of the lip 14 and the entrance portion 21 of the top component A and this locking action provided by the annular ring 25, a highly effective releasable but gas-tight connection is provided by the top and bottom components.

The receptacle portions 11 of the bottom component B have a cylindrical entrance portion 13, as previously indicated, a peripheral wall 11a of a generally fruso-conical configuration and a bottom wall 11b. The side wall 11a is provided with a multiplicity of closely spaced ribs designated by the numeral 19 which serve to provide resiliently expandable wall panel portions 15 therebetween 'which are curved inwardly between the cylindrical entrance portion 13 and a point adjacent the bottom wall 11b. Accordingly, the inside diameter of the panel portions 15 is less than the inside diameter of the ribs 19 at a common plane so that an egg received within the receptacle portion 11 will be resiliently supported by the panel portions 15 at its surface adjacent its relatively strong end portion. By pleating the panels 15 the resilience and expandability thereof is increased so that such structure are preferred for larger and accordingly heavier eggs.

To enhance the stiffness of the bottom component B, it is provided with a peripheral flange 17 to which strengthening boards or elements 18 are attached so as to rigidify the container along its longitudinal axis. These boards may be stiff paper, plastic or other suitable material and the outer surface of the board 18 provides a surface upon which advertising legends or other material may be printed or affixed. Also provided in the web portion 12 of the bottom component B are generally cylindrical depressions 12a which act as stiffening members in the central portion between the adjacent pairs of receptacle portions 11.

Thus it can be seen that the bottom component B is desirably fabricated from a resiliently flexible sheet material which may be opaque and acts to support the egg or other articles in a resilient manner while simultaneously being configured and constructed so as to provide a relatively rigid container in combination with the top component A for purposes of shipping, stacking and storage. The top component A serves to position the eggs and prevent their rattling, and the two components are united in a substantially gas-tight manner so that a. pro tective atmosphere introduced into the receptacle portions designated 11, 20 will be retained therein until such time as the individual cells are opened.

As previously indicated, various thermoplastic materials may be used for the container components depending upon the desired properties, the nature of the inert gas be ing employed and whether a coating is to be applied thereto. As used herein, the term thermoplastic material is intended to include thermoplastic materials per se, such materials when coated either before or after forming, and laminates of two or more thermoplastic materials.

Thus it can be seen that the present invention provides a novel and relatively economical package for perishable goods utilizing a protective atmosphere about the goods which minimizes the tendency to spoil. In addition, the package desirably provides a high degree of protection to the goods therein against the normal shocks involvedin handling and shipping the package, and it also permits the removal of one or more articles from the package without destroying the protective atmosphere about the remaining articles. Since the package lends itself thermoformirig operations, it can be readily and relatively inexpensively formed from thermoplastic sheet materials and may be filled with the goods and the protective atmosphere in automatic equipment or in very simply constructed facilities adapted to small producers.

Having thus described the invention, I claim:

1. A sealed package comprising:

(A) a plurality of avian eggs comprising a frangible outer shell, a yolk and albuminous liquid;

(B) a sealed container of thermoplastic material en closing and resiliently seating said eggs and having top and bottom receptacle components, each of said top and bottom components providing cooperating receptacle portions receiving a portion of one of said eggs, said components having sealing means thereon providing releasable, substantially gas-tight engagement therebetween and providing an individual sealed cell for each of said eggs, said portions of said bottom component including resilient seating means providing support for said eggs and permitting the flow of gas thereabout; and

(C) a gaseous atmosphere in said receptacle portions of said components about said eggs comprising about 96-9975 percent by volume of nitrogen and about 4-0.25 percent by volume of oxygen providing protection -against deterioration and cushioning for said eggs, said material of said container being substantially impermeable to said gaseous atmosphere.

2. The package in accordance with claim 1 wherein said material is composed of polyvinylidene chloride resin.

3. The package in accordance with claim 1 wherein said gaseous atmosphere has relative humidity of about 85 percent at 80 Fahrenheit.

4. The package in accordance with claim 1 wherein each of said receptacle components has a web portion and a plurality of laterally projecting receptacle portions and wherein said sealing means provides a press-fitting connection and includes an axially extending annular rim projecting from said receptacle portions of one of said receptacle components in telescopic engagement with a cooperating recess in said receptacle portions of the other of said receptacle components.

5. The package in accordance with claim 4 wherein said recess is provided by the entrance portion of said receptacle portion of said other component and wherein said sealing means providing a press-fitting connection includes an inwardly-directed annulus on the entrance portion of said receptacle portion of said one receptacle component removably locking said rim in telescoping union therewith.

6. The package in accordance with claim 4 wherein said receptacle components have weakened areas in said Web portions permitting facile severance of an individual receptacle portion.

7. A sealed package of avian eggs comprising;

(A) a plurality of avian eggs comprising a frangible outer shell, a yolk, and albuminous liquid;

(B) a sealed container enclosing and resiliently seating said eggs, said container comprising a first receptacle component of flexible thermoplastic material and a second receptacle component of relatively rigid thermoplastic material, each of said receptacle components having a web portion and a plurality of laterally projecting receptacle portions having a curvilinear entrance portion aligned with the receptacle portion of the other component to provide chambers each enclosing and seating one of said eggs, said first component including means providing resilient support for said egg and permitting the flow of gas thereabout, interfitting sealing means on said components providing a press-fitting connection extending continuously about the periphery of the entrance portion of each receptacle portion of each said member, and means releasably locking said press-fitting connections against accidental opening to releasably lock said receptacle portions in substantially gastight engagement and provide individual sealed chambers for each of said eggs; and

(C) a gaseous atmosphere in said receptacle portions of components about said eggs comprising about 96-9975 percent by volume of nitrogen and about 4-0.25 percent by volume of oxygen, providing protection against deterioration and cushioning for said eggs, said material of said container being substantially impermeable to said gaseous atmosphere.

8. The package in accordance with claim 7 wherein said receptacle components have weakened areas in said web portions permitting facile severance of an individual receptacle portion.

9. The package in accordance with claim 7 wherein said container includes strengthening means on said resilient component rigidifying said container.

10. The package of claim 7 wherein said means comprise a sidewall provided with a multiplicity of closely spaced ribs and inwardly curved resiliently expandable wall panel portions therebetween.

11. The package in accordance with claim 7 wherein said sealing means provides a press-fitting connection and includes an axially extending annular rim projecting from one of said receptacle components in telescopic engage ment with a cooperating recess in the other of said receptacle components.

12. The package in accordance with claim 11 wherein said recess is provided by the entrance portion of said receptacle portion of said other component and wherein said sealing means providing a press-fitting connection includes an inwardly-directed annulus on the entrance portion of said receptacle portion of said one receptacle component removably locking said rim in telescoping union therewith.

References Cited UNITED STATES PATENTS 2,858,224 10/1958 Darrah 99-161 3,239,360 3/1966 Dixon 99154 3,257,062 6/1966 Whiteford 229-2.5 1,645,813 10/1927 Lawler 99-161 3,102,777 9/1963 Bedrosian et al. 99161 X ALVIN E. TANENHOLTZ, Primary Examiner S. B. DAVIS, Assistant Examiner US. Cl. X.R. 

